I ran across this project to build a standalone USB MIDI host/hub: USB HOST midi interface with Raspberry Zero I ordered the pieces and put it all together and it works great. It is tiny and costs less than $50 for everything. Plug in your USB MIDI gear, turn on the power and they are all automatically connected to each other. Excellent for live performance/jams where you don’t want to/can’t use a laptop, don’t have space, etc. Runs off USB power, so you need a 5v micro USB power brick (cellphone charger), or can run easily off a power bank.